In industrial automation and control applications, sensor networks have been widely deployed to support sensing, monitoring, and control of various process variables through wireless communications. Ideally, wireless communication links perform as well as wired communication links. In reality, however, wireless communications suffer from a number of problems in industrial facilities. For example, wireless communications in industrial facilities are often limited by severe fading due to a wide variety of obstacles, such as plant structures, giant machines, and the mobility of humans. To achieve adequate communication reliability and performance for process control systems, it is often necessary to deploy more sensor networks or network components in a given area. This typically increases the cost and complexity of the overall system.